My engine is leaking oil from the engine verandah seal (that's what mechanic said). Also it burns blue smoke out of the tail pipe when started in the morning or after longer periods of idling, that indicates damaged valve stem seals.

I got a quote form a mechanic to re-seal the engine verandah with silicone and replace valve stem seals at about $600. And he did not guarantee that this will stop the smoke 100%.

Given the odd behaviour of the engine I thought it may as well be better to replace it with a second hand one with lower mileage. The same mechanic quoted $1250 for an ED 4.0 litre engine with 140.000 kms on the clock including installation.

I would greatly appreciate your views on the price of an engine swap and would I need new ECU from an ED or the existing one will do?

I need to give him an answer about the engine by tomorrow morning or they may sell it to somebody else.

Also what is the real difference between an ED and EF-EL engines, perhaps it would be better to go for an EF-EL engine?